[auth-service] Disable memcache for Datastore entities
[auth-service] Disable memcache for Datastore entities

This is so that we can implement Datastore writes in the Go version of the service and have those writes be visible from the Python version.

Bug: 1336134
Change-Id: I3816a5ff2201f771c0ecd5589979776a06c8f3be
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/3697713
Reviewed-by: Camilo Jacomet <1363b4c7e89133117bb51cebd53728936346a83c@google.com>
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Commit-Queue: Joey Scarr <e609d4c46132d2dea94acf5ac2b9f229ffc1f245@google.com>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py